Aspiration thrombectomy catheter system, and associated methods

ABSTRACT

An aspiration thrombectomy catheter system includes an aspirator and an aspiration catheter for insertion in a blood vessel. The catheter has a shaft with a proximal end for connection with the aspirator and a tapering distal end with a tip for insertion in the vessel. A plurality of aspiration ports are arranged in sets along the tapering distal end, for aspirating thrombus from the vessel. At least one aspiration lumens within the shaft conducts thrombus from the vessel, through the aspiration ports, to the aspirator. Variably sized or shaped ports provide differing aspiration vectors for enhanced thrombus removal. The aspiration thrombectomy catheter additionally provides for uniform drug dispersion at a thrombotic area, alone or in combination with aspiration of the thrombus. In the event of an adverse reaction, drug dosage may be easily reduced by aspirating dispersed drugs back into the catheter.

RELATED APPLICATIONS

This application claims priority of U.S. Provisional 60/757,790, filedJan. 6, 2005 and incorporated herein by reference.

BACKGROUND

Coronary artery thrombus may be a cause of, or a culprit in, acutecoronary syndromes such as acute myocardial infarction and unstableangina. The presence of thrombus in the coronary artery, accompanying asignificant artherosclerotic plaque narrowing, complicates optimalrevascularization by percutaneous techniques such as angioplasty orstenting.

Distal embolization of thrombus into the distal coronary artery macroand micro circulation, which may for example occur during balloonangioplasty or coronary stenting, results in reduced TIMI (Thrombolysisin Myocardial Infarction) flow. Reduced TIMI flow or flow grade has beendemonstrated to reduce patient outcomes in such studies as the PAMI(Primary Angioplasty in Myocardial Infarction) stent trials and theCADILLAC (Controlled Abciximab and Device Investigation to Lower LateAngioplasty Complications) clinical trials.

Dealing with coronary thrombus in these situations has been the subjectand focus of many pharmacologic and endovascular techniques.Endovascular techniques of thrombus removal by thrombectomy devices havebeen well studied and several existing devices have been tried, such asthe Possis AngioJet® System, which theoretically allows a physician toinfuse medication directly into a thrombus and/or remove the thrombusthrough power pulse aspiration. Unfortunately, clinical trials conductedwith the AngioJet® System have failed to demonstrate an advantage overprevious techniques for treating coronary thrombus, such as balloonangioplasty prior to implantation of a stent.

Other means of treating coronary thrombus include passive aspiration byend-hole aspiration thrombectomy catheters such as the Export aspirationcatheter. The Export aspiration catheter consists of a 5 French monorailcatheter connected to an evacuated 20 ml syringe used to removethrombotic debris. While rather extensively used, the efficacy of thistreatment is limited by thrombus plugging the end hole during theprocedure. Other, newer passive aspiration catheters like the Diver CE(manufactured by V3, Inc.) include a few side holes along the catheterbody near the end of the aspiration catheter; yet such catheters are aptto plug with only slightly more thrombus than necessary to plug thepassive export catheter.

SUMMARY

The aspiration thrombectomy catheter system disclosed herein mayovercome problems associated with prior devices to provide thrombusremoval and drug dispersion in coronary arteries or arterial conduits,such as saphenous vein bypass grafts or peripheral arteries.

In one embodiment, an aspiration thrombectomy catheter system includesan aspirator and an aspiration catheter for insertion in a blood vessel.The aspiration catheter has a shaft with (a) a proximal end forconnection to the aspirator and (b) a tapering distal end with a tip forinsertion in the vessel. A plurality of aspiration port sets, eachhaving a plurality of ports for aspirating thrombus from the vessel, arearranged along the tapering distal end. At least one aspiration lumenswithin the shaft conducts thrombus from the vessel, through theaspiration ports, to the aspirator.

In one embodiment, a method for aspirating thrombus includes advancingan aspiration catheter within a vessel until at least a distal set ofaspiration arranged along a distal portion of tapering catheter tip isproximate a thrombus. Aspiration forces are applied through at least thedistal set of aspiration ports to suction at least a first portion ofthe thrombus into a first aspiration lumens. The aspiration catheter isadvanced through unaspirated thrombus and aspiration forces are appliedvia at least one second set of aspiration ports arranged proximal to thedistal set of aspiration ports, along the tapering catheter tip, tosuction at least a second portion of the thrombus into the aspirationcatheter.

In one embodiment, a method for aspirating thrombus includes advancingan aspiration catheter within a vessel to an occluding thrombus. One ormore lytic agents are dispersed from a first catheter lumens to thethrombus via a first set of ports opening into the first catheterlumens. Aspiration forces are applied to the thrombus via at least asecond set of ports, the second set of ports conducting aspiratedthrombus into a second catheter lumens.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one embodiment of an aspiration thrombectomy cathetersystem including an aspiration thrombectomy catheter.

FIG. 2 shows the aspiration thrombectomy catheter of FIG. 1 in a sectionof artery.

FIG. 3 is a flow-chart illustrating a method of aspirating thrombus, forexample using the aspiration thrombectomy catheter of FIG. 1.

FIG. 4 illustrates drug dispersion proximate a thrombus, with theaspiration thrombectomy catheter of FIGS. 1 and 2.

FIG. 5 is a flow-chart showing a method of delivering thrombolyticdrugs, for example using the aspiration thrombectomy catheter of FIGS.1, 2 and 4.

DETAILED DESCRIPTION

It is appreciated that the present teaching is by way of example, notlimitation. The illustrations herein are not limited to use orapplication with a specific type of aspiration thrombectomy catheter.Thus, although the instrumentalities described herein are for theconvenience of explanation, shown and described with respect toexemplary embodiments, it is appreciated that the principals herein maybe equally applied in other embodiments of aspiration thrombectomycatheters.

For example, for ease of discussion, aspiration thrombectomy cathetersystem 100 is described herein below with respect to removal of coronarythrombus; however, those skilled in the art will recognize, afterreading and fully appreciating the present disclosure, that system 100may be equally applied for enhanced thrombus removal elsewhere in thecirculatory system. For example, system 100 may be applied in:

-   -   Removal of thrombus in the carotid circulation, both        extra-cranial and intra-cranial;    -   Removal of visceral thrombus, for example from arteries        supplying digestive organs and/or from arteries supplying the        kidneys;    -   Removal of peripheral vascular thrombus, for example from the        legs;    -   Thrombus removal in surgically created arterial venous fistulas        for hemodialysis, for example using cross-catheter thrombectomy;    -   Removal of thrombus from synthetic dialysis access grafts;    -   Removal of thrombus from surgically created synthetic or native        vein bypass grafts (both harvested and transplanted and in-situ        vein grafts);    -   Removal of thrombus from a stent;    -   Removal of stenosis from a stent or surgically created fistula,        dialysis access or vein bypass graft;    -   Isolated and uniform drug dispersion through aspiration ports,        e.g., during any of the above procedures; and    -   Readily customizable dosage (e.g., amplification and/or        reduction) as a function of real-time patient response to        dispersed drugs.

As used herein, the term “vessel” refers to any circulatory conduit,including but not limited to the aforementioned arteries, veins,fistulas, grafts and stents.

FIG. 1 shows an aspiration thrombectomy catheter system 100. System 100includes a catheter 102 having a shaft 104. Shaft 104 has one or moreproximal ends (not shown; see however FIG. 4) for connection with one ormore aspirators, and a distal end or section 106. As shown in FIG. 1, adistal end 106 has a plurality of aspiration holes or ports 108,arranged in a plurality of sets 110. As used herein, a set of portsindicates two or more ports grouped in close proximity to one another.In one embodiment, distal section 106 includes three sets 110A-110Chaving ports 108A-C, respectively. Sets 110A-C may be arranged as distalset 110A, middle set 110B and proximal set 110C, with respective ports108A (distal ports), 108B (middle ports) and 108C (proximal ports)opening into one or more aspiration port channels/lumens.

Distal end/section 106 of catheter 102 is for example inserted into thecirculatory system on a needle and advanced to an occlusion in a small,medium or large artery; therefore, system 100 may be sized for thedesired use (as used herein, the terms “occlusion” and “occluding” mayrefer to partial or complete occlusion or occluding of a vessel). Distalsection 106, and optionally all or a portion of shaft 104, may be formedor coated with a smooth or low-friction material such as Teflon, tofacilitate advancement of catheter 102. Further, catheter 102 may beconfigured as a single or a dual aspiration catheter. When catheter 102is a single lumen aspiration catheter, an aspirator attaches to theproximal end of the catheter. When catheter 102 is a dual lumenaspiration catheter, shaft 104 branches to form two proximal ends forconnection with one or more aspirators.

Distal section 106 tapers proximally to distally from a shoulder 116 toa tip 118. Tip 118 and/or a portion or all of distal section 106 is forexample formed or covered with a soft material 107 to minimize vesseltrauma, while part or all of shaft 104 is stiffer, to prevent kinkingand facilitate advancement and torqueability of catheter 102 within avessel, such as a coronary artery. Walls 120 of shaft 104, andoptionally distal section 106, for example include medically acceptablerigid polymers, co-polymers or metals, such as plated or unplatedstainless steel, ELGILOY, platinum, a shape-memory alloy such asnitinol, or combination thereof. In one embodiment, shaft 104 is aflexible tube reinforced with one or more of the above polymers,co-polymers and/or metals. Such reinforcement materials may be wired,braided or coiled through or within shaft 104. Proximal-to-distalflexibility may be increased by decreasing braid, coil or wire densityfrom proximal end/s to distal section 106 or tip 118. A degree ofreinforcement within distal section 106 for example provides for asoft-tipped catheter 102 that resists twisting or wrapping of tip 118and/or distal section 106 during advancement or rotation.

A wire 122 guides catheter 102 in a vessel, e.g., artery 200, FIG. 2.Catheter 102 may be a monorail or fixed wire catheter (e.g., to allowfor smaller diameters) or an over-the-wire catheter. That is, wire 122may be fixed with catheter tip 118, with a set distance between tip 118and a wire tip 124, or catheter wire 122 may be a separate andunattached guide wire over which catheter 102 rides.

In one embodiment, catheter 102 is an over-the-wire catheter (for easeof illustration, the wire lumen of the catheter is not shown).Over-the-wire catheters often ride in the center of straight segments ofan artery. As catheter 102 advances into an arterial thrombus, vacuumforces provided at a certain magnitude through ports 108A-C of taperingdistal section 106 aspirate thrombus, for example from the inside-out,via ports 108A, 108B and 108C. As distal section 106 encountersthrombus, vacuum forces provided through ports 108A aspirate nearbythrombus. As thrombotic material is generally cohesive, thrombus drawninto ports 108A (and/or 108B, 108C) may pull additional thrombus intocatheter 102. Portions of thrombus that are not pulled into catheter 102by cohesion, e.g., portions that are too far away for aspiration throughports 108A, may be drawn inward and closer to middle and/or proximalports 108B, 108C, by vacuum forces. As middle/proximal ports 108B, 108Care positioned on wider portions of distal end 106 than ports 108A,aspiration is further facilitated as catheter 102 advances within thevessel and the distance between the vessel walls and adhered thrombus,and ports 108A-108C successively decreases. Increased proximity betweenremaining thrombus and ports 108B, 108C (e.g., provided both by inwardpull through ports 108A and the taper of distal section 106), forexample allows the same magnitude of vacuum force applied through distalports 108A to effectively aspirate remaining thrombus through ports108B, 108C. The effective surface area of thrombus aspirated is therebyincreased.

The tapering design of catheter 102 may further provide increasedthrombus-to-port contact or proximity over the prior art. For example,prior art French catheters have essentially the same diameter fromproximal end to distal end. Aspiration ports of such a prior artcatheter are therefore located farther and farther from remaining,unaspirated thrombus as the catheter advances in the artery. A prior artcatheter of essentially uniform diameter may be unable to effectivelyremove intimal thrombus, whereas the tapering design of catheter 102provides increasing proximity between distal-to-proximal aspirationports and medial-to-intimal thrombus, respectively, as catheter 102advances therethrough. For example, thrombus that is pushed or wedgedaway from distal aspiration ports, such as ports 108 (e.g., pushedagainst the vessel wall by a guide wire or fixed wire) may be aspiratedvia middle or proximal ports 108B, 108C of catheter 102, whereas theprior art French catheter may be unable to aspirate the displacedthrombus due to the increased port-to-thrombus distance. In addition,Catheter shoulder 116 may trap unaspirated thrombus, providing anextended opportunity for aspiration through proximal ports 108C, e.g.,during withdrawal of the catheter.

As shown in FIG. 1, catheter 102 has a proximal, or first aspirationlumens 112 (hereinafter referred to as first lumens 112) for aspirationthrough proximal ports 108C, and a middle-distal, or second aspirationlumens 114 (hereinafter referred to as second lumens 114) for aspirationthrough middle and distal ports 108B, 108A. Distal, middle and proximalports 108A, 108B and 108C may be sized, shaped and/or orienteddifferently from one another. FIG. 1 illustrates round distal ports 108Aand elliptical middle and proximal ports 108B, 108C of differing sizeand orientation. However, other arrangements of port shapes and sizesare within the scope hereof. For example, all of ports 108A-C may beelliptical, with ports 108B, 108C of middle and proximal sets 110B, 110Cdiffering in orientation and/or size from distal ports 108A of set 110A.Alternately, ports of sets 110A-C may be similarly sized and shaped, butdifferently oriented. Such variation in port size, shape and/ororientation provide system 100 with a variety of vortices and aspirationvector forces (directions and/or magnitudes), for enhanced thrombusremoval over prior art catheters having fewer ports of essentially thesame size, shape and orientation. Sets of small ports for exampleenhance aspiration by the Venturi effect, speeding flow of aspiratedthrombus into aspiration lumens 112/114, while larger port sets allowfor aspiration of larger thrombotic particles.

FIG. 2 shows system 100 in a section of artery 200 partially occluded bythrombus 202. As wire 122 and catheter 102 advance through thrombus 202,aspiration port sets 110A-110C successively contact or come intoproximity with innermost, middle and intimal layers 204, 206, 208 ofthrombus 202. Aspiration of innermost, middle and intimal layers 204-208may occur as illustrated by directional aspiration arrows 210.Aspiration is facilitated by increased thrombus-to-port contact orproximity provided by catheter 102, thus facilitating removal of agreater thrombus burden as the catheter advances through the vessel. Theplurality of ports 108A-C may also minimize plugging by organized orlarge thrombus aggregates, as is seen with prior art end-hole cathetersor prior art catheters having fewer side ports.

The tapered design of catheter 102 may reduce distal embolization ofthrombus. For example, as a catheter advances through thrombus, portionsof the thrombus may be loosened, but not aspirated. Prior art designshaving substantially uniform catheter or distal section diameter may notcome into close enough proximity to aspirate portions of thrombusclinging to the intima, for example; however, this intimal thrombus maybe loosened. The loosened thrombus may break free and embolize in distalarterial conduits. The tapering shaft of catheter 102 may reduce thisdistal embolization because aspiration ports 108A-C come closer to thevessel walls and any thrombus clinging thereto as the catheter advances.Thrombus loosened during aspiration by ports 108A or 108B is for exampleaspirated when ports 108C come into proximity or contact with theloosened thrombus.

System 100 may also enhance thrombectomy when utilized in a curvedsection of artery. Aspiration port sets 110A-C approach thrombus on anarterial wall in closer and closer succession, due to the taperingdesign of catheter 102. Thus, catheter 102 may thus also remove thrombus202 medially-to laterally in a curved section of artery, as describedherein above with respect to FIG. 2.

FIG. 3 is a flow chart illustrating a method 300 of aspirating thrombus.An aspiration catheter, such as catheter 102 on wire 122, is insertedinto an artery, in step 302. A tapering distal end of the catheter,e.g., end 106 of catheter 102, is advanced into the thrombus, in step304. Thrombus is aspirated through distal aspiration ports of thecatheter and through an aspiration lumens, for example ports 108A andsecond lumens 114, in step 306. As the catheter is advanced further intothe blocked artery, middle ports such as ports 108B are brought intocontact with or proximal to unaspirated portions of the thrombus, instep 308. These portions are aspirated through an aspiration lumens,such as second lumens 114, via the middle ports, in step 310. Catheter102 is advanced yet further into the blocked artery, such that proximalports of the catheter, e.g., ports 108C, are brought into contact withor proximal to remaining portions of the thrombus that were notaspirated through the middle ports, in step 312. These remainingportions of thrombus are aspirated through an aspiration lumens such asfirst lumens 112, via the proximal aspiration ports, in step 314.

Continued aspiration during withdrawal of catheter system 100 mayfurther enhance thrombus removal. Once the catheter has traveled pastthrombus, it may aspirate remaining thrombus during withdrawal backthrough the artery. Catheter 102 may, for example, trap remainingthrombus between the catheter shoulder 116 or shaft 104 and the arterialwall during an antegrade pass. The trapped thrombus may then beaspirated through proximal-to-distal ports 108C-108A as the catheter iswithdrawn. Accordingly, the catheter is advanced until aspiration ports(such as port sets 110A-110C) have passed through the thrombus, in step316. The catheter is withdrawn back through any remaining thrombus, instep 318. The proximal, middle and distal aspiration ports aspirateremaining thrombus, in step 320.

Steps 302-320 need not be performed in the order described in connectionwith FIG. 3. For example, thrombus may be aspirated through aspirationports while catheter 102 is simultaneously and continually advancedthrough a thrombus. Also, not all of steps 302-320 need necessarily beperformed for effective thrombus removal. For example, if thrombus iscompletely removed during an antegrade pass therethrough, it may not benecessary to aspirate while withdrawing catheter 102.

The proximal end or ends of catheter 102 are connectable with aninfusion device, such as a syringe, allowing use of thrombectomycatheter system 100 in thrombolysis, for example to lyse deep andsuperficial venous thrombi, or in cross-catheter thrombolysis insurgically created arterial venous fistulas. A lytic agent or agents,e.g., Reteplase or Alteplase, is infused via aspiration lumens 112and/or 114, for precise and uniform dispersion through ports 108A-108C.FIG. 4 depicts an aspiration thrombectomy catheter system 400 forremoving thrombus from partially occluded vessel 200. Vessel 200 is forexample blocked by thrombus 202 as described above with respect to FIG.2. Catheter 102 is inserted into vessel 200 and advanced to thrombus202. Catheter 102 may again be an over-the-wire or a fixed wirecatheter. In one embodiment, catheter 102 is a fixed wire or monorailcatheter 102, with wire 122 securely formed with catheter tip 118 (seeFIG. 1). Wire 122 guides distal section 106 to and/or partially throughthrombus 202, where aspiration may be applied as previously described.

Optionally or additionally, catheter 102 connects to a drug dispenser ordrug delivery apparatus, such as a gravity flow system, an automated ormanually operable pump, a syringe or other intravenous drug dispenser.Such a dispenser is illustratively shown in FIG. 4 as a syringe 402 (notto scale). Once distal section 106 is positioned as desired, relative tothe thrombus, lytic agents are for example delivered through lumens 112and/or 114 and out one or more of port sets 110A-110C, as indicated bydispersion arrows 404. System 400 thus provides isolated drug deliverywith uniform dispersion from each port 108A-108C, at theoccluded/thrombotic area. Alternately, system 400 provides targeted drugdelivery via selected ports or port sets 108, 110, while remaining portsor port sets may be used in aspirating loosened thrombus, deliveringcomplementary lytic agents, e.g., in sequence, or reducing dosage in theevent of overdose or adverse patient reaction.

In one embodiment, lumens 114 connects with or extends into tubing 406which in turn connects to syringe 402. Tubing 406 for example conducts athrombolytic, antibiotic or otherwise therapeutic drug from syringe 402,through lumens 114, to proximal ports 108C. Should an adverse reactionsuch as bleeding occur, dosage may be quickly reduced by aspirating thedelivered drug back through proximal ports 108C, for example by drawingback on syringe 402. It will be understood that lumens 112 may likewiseconnect, via tubing 408, to a drug or lytic agent dispenser or deliverysystem such as a second syringe, to facilitate delivery of desired drugcombinations or sequences, e.g., via middle and distal ports 108B, 108A.Likewise, one of lumens 112, 114 may connect via tubing 406, 408 with anaspirator while the other of lumens 112, 114 connects with the drugdispenser. In the case of an adverse drug reaction, dosage may bequickly reduced by aspirating drugs released via one set of ports 110back through another set of ports 110. For example, lytic drugsdelivered to lumens 114 and dispersed through proximal ports 108C may beaspirated back through distal and middle ports 108A, 108B, incommunication with lumens 112. Aspiration thrombectomy catheter system400 may also be used to alternately or simultaneously disperse lyticagents and remove/aspire thrombus loosened by the lytic agents.Likewise, a combination of ports 108A-C may be used in aspiration ordrug dispersion.

FIG. 5 is a flowchart illustrating one method 500 for removing thrombuswith an aspiration thrombectomy catheter. In step 502 an aspirationthrombectomy catheter is inserted into a vessel. In step 504, thecatheter is advanced to a thrombus. In one example of steps 502, 504,catheter 102 is inserted into an artery and advanced until distalsection 106 contacts or is proximate the thrombus. When the catheter isin position, e.g., distal section 106 is proximate or contacting thethrombus, drugs are dispersed, in step 506. In one example of step 506,drugs are applied to tubing 406 via a drug dispenser. Drugs travel intolumen 112 and out of ports 108C.

The patient undergoing method 500 is monitored, in step 508, e.g., forbleeding or other adverse reactions to lytic drugs. If (decision 510) anadverse reaction occurs, released drugs are aspirated, in step 516. Inone example of step 516, upon determining that an overdose or adversereaction has occurred, released lytic drugs are aspirated back intocatheter 102 via distal and medial aspiration ports 108A, 108C. Lumen114, in contact with ports 108A, 108C, connects with tubing 408 which inturn connects with an aspirator, such as a syringe. The aspirator orsyringe is activated to “vacuum” the lytic drugs from the vessel.

Dotted box 517 indicates optional steps during or in combination withaspiration step 516. In optional step 518, the catheter is advanceduntil all aspiration ports have passed through the thrombus. In step520, the catheter is withdrawn through the thrombotic area. Steps 518,520 may be repeated as desired to facilitate aspiration of athrombolytic agent that has dispersed within the vessel, or to aspiratethrombus loosened by the thrombolytic agent, as described below.

Returning to method 500, if (decision 510) there is no adverse reactionor overdose and if (decision 512) drug delivery is complete, method 500continues with decision 514. If (decision 514) thrombus is to beaspirated, aspiration commences in step 516. Optional steps 518, 520 maybe repeated until the desired or maximum amount of thrombus has beenremoved from the vessel. In one example of steps 516-520, whereaspiration is desirable, tubing 404 is disconnected from theaforementioned drug dispenser or delivery system, e.g., syringe 402,FIG. 4, is switched to an aspiration mode. As catheter 102 is advancedthrough (step 518) and withdrawn from (step 520) the thrombotic area,vacuum forces are applied via aspiration ports 108A, 108B and 108C untilthe thrombus is satisfactorily removed from the vessel walls. Once thethrombus is satisfactorily aspirated, the catheter is removed, in step522. In one example of step 522, catheter 102 is withdrawn from the bodyof a patient undergoing method 500.

In one example of steps 506-522, a thrombolytic agent is dispersed viadistal port set 110A, FIG. 1. As noted, distal port set 110A may openinto a lumens independent of the lumen or lumens associated with middleand proximal port sets 110A, 110B. If desired, a second thrombolyticagent is dispersed via middle or proximal port sets 110A, 110B. Thesecond thrombolytic agent may be dispersed synchronously with the agentdispersed via distal ports 108A, or the two agents may be alternated orpulsed to achieve a desired drug combination or amount proximate thethrombus.

When drug delivery, or a drug delivery cycle, is complete, thrombusloosened by drug therapy is for example aspirated as described above,through one or more of port sets 110A-110C. Catheter 102 may be advancedand withdrawn back and forth through the thrombotic region during (orinterspersed with) aspiration), to enhance thrombus removal. Catheter102 may likewise be rotated such that port sets 110A-C along distalsection 106 vacuum the entire inner circumference of the vessel. Whenthrombus is satisfactorily removed, catheter 102 is withdrawn from thepatient's body, step 522.

Although not shown in FIG. 5 (for ease of illustration), it will berecognized that drug delivery step 506 and aspiration steps 516-520 maybe repeated as desired prior to removal of catheter 102 (step 522). Forexample, where decision 516 pertains to one of multiple drug deliverycycles, method 500 may move from aspiration steps 516, 518 or 520 backto drug dispersion at step 506.

Changes may be made in the above systems and structures withoutdeparting from the scope thereof. It should thus be noted that thematter contained in the above description and/or shown in theaccompanying drawings should be interpreted as illustrative and not in alimiting sense. The following claims are intended to cover generic andspecific features described herein, as well as all statements of thescope of the present system and structures, which, as a matter oflanguage, might be said to fall therebetween.

1. An aspiration thrombectomy catheter system, comprising: an aspirator;and an aspiration catheter for insertion in a blood vessel, theaspiration catheter having: a shaft with (a) a proximal end forconnection to the aspirator and (b) a tapering distal end with a distaltip for insertion in the vessel; a plurality of aspiration port setsarranged along the tapering distal end, each of the aspiration port setshaving a plurality of ports for aspirating thrombus from the vessel, andat least one aspiration lumens within the shaft, for conductingaspirated thrombus from the vessel, through the aspiration ports, to theaspirator.
 2. The system of claim 1, wherein the ports of eachaspiration port set differ in one or both of size and shape.
 3. Thesystem of claim 2, the differently sized or shaped aspiration portsproviding differing vector forces for aspiration of thrombus.
 4. Thesystem of claim 3, the differently sized or shaped aspiration portsincluding small, medium and large ports for producing Venturi forces ofvarying strength to aspirate the thrombus into the lumens.
 5. The systemof claim 1, the aspiration catheter comprising a dual aspirationcatheter having a first aspiration lumens and a second aspirationlumens.
 6. The system of claim 5, the plurality of aspiration port setscomprising a proximal port set opening into the first aspiration lumens,and a middle and a distal port set opening into the second aspirationlumens; wherein the first aspiration lumens conducts aspirated thrombusfrom the proximal port set to the aspirator and the second aspirationlumens conducts aspirated thrombus from the middle and distal port setsto the aspirator or a second aspirator.
 7. The system of claim 6,further comprising a first tube connecting the first lumens to theaspirator and a second tube connecting the second lumens to theaspirator or the second aspirator.
 8. The system of claim 1, the shaftcomprising a shoulder defining a taper of the shaft to the distal tip.9. The system of claim 1, further comprising a dispenser for dispersinglytic agents through one or more of the aspiration port sets to thethrombus.
 10. A method for aspirating thrombus from a vessel,comprising: advancing an aspiration catheter within the vessel until atleast a distal set of aspiration ports arranged along a taperingcatheter tip is proximate a thrombus; applying aspiration forces throughat least the distal set of aspiration ports to suction at least a firstportion of the thrombus into a first aspiration lumens; advancing theaspiration catheter through unaspirated thrombus; and applyingaspiration forces via at least one second set of aspiration portsarranged along the tapering catheter tip and proximal to the distal setof aspiration ports, to suction at least a second portion of thethrombus into the aspiration catheter.
 11. The method of claim 10,further comprising withdrawing the catheter through the thrombus whileaspirating through one or more of the distal and the at least one secondset of aspiration ports.
 12. The method of claim 12, wherein applyingaspiration forces through the distal set of ports comprises activating afirst aspirator and applying aspiration forces through the at least onesecond set of ports comprises activating a second aspirator.
 13. Themethod of claim 12, further comprising dispersing lytic agents at thethrombus through one or more of the distal set of aspiration ports andthe at least one second set of aspiration ports, prior to applying theaspiration forces.
 14. The method of claim 12, wherein advancing theaspiration catheter comprises advancing the aspiration catheter over aguide wire.
 15. The method of claim 10, wherein suctioning at least asecond portion of the thrombus into the aspiration catheter comprisessuctioning at least the second portion into a second aspiration lumens.16. A method for aspirating thrombus from a vessel, comprising:advancing an aspiration catheter within the vessel to an occludingthrombus; dispersing one or more lytic agents from a first catheterlumens to the thrombus via a first set of ports opening into the firstcatheter lumens; and applying aspiration forces to the thrombus via atleast a second set of ports, the second set of ports conductingaspirated thrombus into a second catheter lumens.
 17. The method ofclaim 16, further comprising repeating the steps of dispersing andapplying, to loosen and remove the thrombus from the vessel.
 18. Themethod of claim 16, further comprising applying aspiration forces to thethrombus via a third set of ports, the third set of ports differing fromthe second set of ports in one or both of size and shape.
 19. The methodof claim 18, the different sizes or shapes of the second and third setsof ports providing multiple aspiration vortices for removing thethrombus from the vessel.
 20. The method of claim 18, the third set ofaspiration ports opening into the second catheter lumens.